Passive chip attenuators are generally used to attenuate signals in a circuit. Various attenuator designs can be used, for example, including different configurations and/or values of resistors in an attenuator circuit design. Such chips often include an attenuator circuit on top side of the chip and a grounding bar on the bottom side of the chip in order to provide a ground signal to the attenuator circuit. Wrap-around contacts generally travel from the bottom side of the chip to the top side by wrapping around the perimeter edge of the chip, permitting the electrical communication of ground and signal from the bottom side of the chip to the attenuator circuit.
Such designs can lead to poor operating quality for attenuators, particularly when attenuating high frequency signals. For example, too narrow of a ground strip can lead to impedance matching issues when attenuating high frequency signals. Impedance mismatch issues at high frequencies can cause signal reflections or other errors, leading to unpredictable and/or undesirable attenuator operation. In addition, many attenuators use only a single ground launch from a circuit board into the attenuator and utilize a single ground trace in a ground-signal (G-S) configuration, which can lead to various signal reflections and losses.
Additionally, wrap-around contacts tend to contribute to impedance matching issues. When attaching a chip with wrap-around contacts to a board, it can be difficult to control the geometry of the solder used for electrically contacting the wrap-around contacts. This can make it difficult to maintain a ground-signal-ground (G-S-G) configuration present on the circuit board when launching from the circuit board (e.g., that includes a G-S-G configuration) to the attenuator circuit. Losing the desired G-S-G configuration, for example, while launching the signal to the chip, can lead to various signal reflections and losses, as well as impedance mismatches, particularly at high frequency operation. Moreover, wrap-around contacts often create 90° angles through which the signal propagates, further contributing to signal reflections and losses, particularly at high frequencies. Additionally, wrap-around contacts can require fabrication techniques separate from those used to construct the rest of the attenuator, such as different material deposition techniques, and can be difficult to construct uniformly, leading to increased cost and time necessary for attenuator fabrication.
Single ground-signal (G-S) configurations combined with common wrap-around contacts can compound the issues that arise in each case when attenuating high frequency signals.
Such design characteristics often limit the high-frequency performance of chip attenuators. Said differently, such characteristics limit the frequency range that such attenuator chips can operate within the desired operating parameters (e.g., amount of desired attenuation). Currently, attenuator chips struggle to operate consistently at frequencies greater than approximately 18 GHz. Thus, as higher frequency signals become more ubiquitous, improvement in attenuator operation at higher frequencies will be needed.